Venom Immunity

In my last post about the beautifully deadly blue ringed octopus I mentioned that even though they are toxic enough to kill 10 men they are immune to their own venom. This topic is of immunity has not been extensively explored and there is no clear answer to why this occurs in some species and not others. I was able to observe the effects of death adder (Acanthophis antarcticus) venom on another of the same species. The male was placed in the female’s enclosure for breeding when the female bit him on the head and envenomation occurred. There was local swelling at the bite site and subdued behaviour for two to three days. After this period the male returned to normal, eating and displaying active behaviours. He was reintroduced to the female and successfully mated. This same scenario has been observed with species such as red belly black snakes (Pseudenchis porphyriacus) and Copperheads (Austrelaps superbus) however the outcome of these incidents resulted in the death of the individual bitten.

The immunity between separate species has been a little more deeply explored. One animal that is famous for its ferocity and fearlessness is the honey badger (Mellivora capensis). This carnivorous mammal is found mainly in Africa where it preys on an array of venomous snakes. The most remarkable attribute about the honey badger is its immunity to snake venoms. This is not a unique trait, there are many ophiophagous (venomous snake eating) mammals which also show an immunity to not only snake venoms but also many arachnid venoms.

https://www.youtube.com/watch?v=wPKlryXwmXk

(15/4/2014-3:10pm)

There have been some evolutionary debates on this topic. One main question is why have all mammals developed and immunity to animal toxins in the case of accidental envenomation’s however it has been hypothesised that accidental envenomation leads to strong avoidance behaviours and only prolonged predation on venomous organisms leads to immunity. A debate that has arisen and is currently being examined is whether venomous species are in an arms race with their prey or their predators.

There has been a lot of focus on this topic due to the medical applications that surrounds venom resistance, however it seems that evolutionary biologist have only just scratched the surface to what may be influencing the evolutionary direction of nature’s deadliest venomous animals.

References:

Voss, R, Jansa, S 2012, "Snake-venom resistance as a mammalian tropic adaptation: lessons from didelphid marsupials",Biological Reviews, vol.87, pp. 822-837.